Have no power to thermostat

How can I help?

How can I help??

I got a new thermostat for a ruud heat pump central heat /air . Well it was not compatible with my unit so I put old one back on and I must have touched some wires together or something cause now I have no juice to the thermostat. Can you help with some suggestions on what to do thanks

Okay if you have a volt meter separate the red wire (R) and the wire that went to (C) or the wire that went to (Y). You should have 24 volts ac across r-y or r-c, If you do not you probably shorted the transformer or blew a low voltage fuse in the airhandler do you have gas or electric heat? And how new is the system?

Sorry you already answered that it sounds like the system probably has a low voltage fuse in it disconnect power to the airhandler unit remove the cover inside you should find a circuit board with a 3 amp pink fuse or a 5 amp orange fuse pull that fuse and check.

Sorry you already answered that it sounds like the system probably has a low voltage fuse in it disconnect power to the airhandler unit remove the cover inside you should find a circuit board with a 3 amp pink fuse or a 5 amp orange fuse pull that fuse and check.


Tested with a voltage meter and there is no power at wires for thermo
Would you happen to know where the fuse might be located:confused:

The fuse should be located on a printed circuit board inside the electrical compartment of the indoor unit will be a pink or yellow little spayed fuse be sure you have the main disconnect off to the indoor unit, if you do not see a small fuse you should see a transformer one side being line w/ incoming voltage at 240 vac and load w/ voltage at 24 vac some transformers have circuit breaker on the transformer however I do not believe ruud does, check to see though, if you do not see a fuse or circuit breaker on the transformer you are going to need to check the transformer( how much you know and trust yourself around electricity will determine your next course of action)

the fuse should be located on a printed circuit board inside the electrical compartment of the indoor unit will be a pink or yellow little spayed fuse be sure you have the main disconnect off to the indoor unit, if you do not see a small fuse you should see a transformer one side being line w/ incoming voltage at 240 vac and load w/ voltage at 24 vac some transformers have circuit breaker on the transformer however i do not believe ruud does, check to see though, if you do not see a fuse or circuit breaker on the transformer you are going to need to check the transformer( how much you know and trust yourself around electricity will determine your next course of action)


I have some one helping me with this who is an electrician but he needs a little help with the unit so I am gathering as much info as I can

Okay, then have him check the transformer for an output of 24vac if you have that but not at the stat you have a bad fuse or bad t-stat wiring, if you do not have 24 vac out of the transformer he should have access to get a 75 va transformer ( it will cost slightly higher than a 40va but will come w/ a circuit breaker on it and next time this occurs wa-lah you reset and away you go. Sounds like you have a bad transformer

okay, then have him check the transformer for an output of 24vac if you have that but not at the stat you have a bad fuse or bad t-stat wiring, if you do not have 24 vac out of the transformer he should have access to get a 75 va transformer ( it will cost slightly higher than a 40va but will come w/ a circuit breaker on it and next time this occurs wa-lah you reset and away you go. sounds like you have a bad transformer

I hope that is not what it is but do you know about how much one will cost

25 to 50 bucks depending on where you live and what supplier you get it through most ac suppliers close at noon today